Apparatus for preventing churning and aeration of liquids in hydraulic systems



July 13, 1954 F. s. FLICK 2,683,463 APPARATUS FOR PREVENTING CHURNINGAND AERATION OF LIQUIDS IN HYDRAULIC SYSTEMS Filed May 24, 1950 v v 2?FIG. 2

FIG. 3

v INVENTQR.

' FRANCIS S."F I ICK l ATTORNEYS.

Patented July 13, 1954 APPARATUS FOR PREVENTING CHURNING AND AERATI ONOF LIQUIDS IN HYDRAU- LIO SYSTEMS Francis S. Flick, Chicago, Ill.,assignor, by mesne assignments, to Miller Fluid Power Company,

a corporation of Illinois Application May 24, 1950, Serial No. 163,892

1 Claim.

This invention relates to apparatus for preventing churning and aerationof liquids in hydraulic systems, and more particularly in fast cyclinghydraulic systems having small tanks for handling the liquid.

In fast cycling hydraulic systems, and especially in such systems havingsmall tanks for handling the liquid, much trouble has been experienced,prior to the present invention, from the churning and undue aeration ofthe liquid 7 in the tank when the liquid enters the tank at one end, andwhen air under pressure is introduced through the other end of the tankfor exerting its pressure against the surface of the liquid in the tankin air-oil circuits. has also been prevalent, prior to my invention, intypical pump circuits in which a pump is used for forcing the oil orother liquid through the circuit.

Such trouble of the tank or tanks, so spaced from the tank inletpipewall, and from the side walls, that the high velocity flow in thesmall area passage of the inlet pipe is converted into a low velocityflow in a large area passage between the bafile and the adjacent tankwalls. This slows up the flow of the incoming liquid or air along thebaflle so that, by the time it has passed through the space between themarginal edge of the baffle and the tank side wall, it will enter thetank in a quiet condition Without causing churning or aeration of theliquid in the pipe. In other words, it spreads out radially in alldirections from the central zone of the bafile and due to such rapidlyincreasing area its velocity of flow is rapidly and progressively slowedup to the marginal edge of the bafiie and then through the space betweenthe baflie edge and the tank wall with the above mentioned lack ofchurning and aeration.

I have found that, in order'to achieve the best results, the height ofthe battle is determined by dividing the circumference of the inlet holeinto the cross sectional area of the inlet hole. For example,

, where D is the diameter of the hol in the inlet pipe. By theexpression height of thebaffie is meant the perpendicular distance fromthe fiat face of the baffle to the adjacent face of the tank end wall inwhich the inlet hole is formed. The distance between the marginal edgeof the bafile and the adjacent side walls of the tank is also of thediameter of the hole in the inlet pipe. This results in converting thehigh velocity flow in the small area passage of the inlet pipe into alow velocity flow in a large area passage between the baflie and thetank head to prevent churning and aeration of the liquid in the tank.

Among the objects of the invention are: to provide a novel and improvedapparatus for preventing churning and aeration of liquids in hydraulicsystems; to overcome the disadvantages and accomplish the advantagesreferred to earlier herein; to provide a bafile which is spaced awayfrom the adjacent tank inlet end wall a distance of approximatelyone-fourth of the diameter of the hole in the inlet pipe; to provide abafile which at its marginal edges is spaced away from the adjacent sidewalls of the tank a distance of approximately one-fourth of the diameterof the hole in the inlet pipe; and such further objects, advantages andcapabilities, inherently possessed by the invention, as will later morefully appear.

The invention is illustrated in a preferred embodiment in theaccompanying drawing in which- Fig. 1 is a longitudinal cross section,partly in elevation, of an air-oil apparatus embodying my invention.

Fig. 2 is a similar view of an apparatus having a pump circuit.

Fig. 3 is an enlarged transverse section of one form of four-way valveusable in the circuit of either Fig. 1 or Fig. 2.

Fig. 4 is an enlarged transverse section on the line i-4 of Fig. 1.

In the embodiment shown in the drawing for illustrative purposes, theapparatus of Fig. '1 comprises a pair of tanks I and 2 connected attheir upper ends by pipes 3 and 4, which pipes at their adjacent endsare connected with a four-way valve 5. Pipes 3 and i at their oppositeends are connected to interior passageways 6 and l in the upper heads 3and 9 of tanks l and 2, respectively. The passageway 5 extends to thevertical center line of tank I, where it joins with an inlet hole I 9opening downwardly through the center of the lower face of the top tankhead 8, to form an inlet for air under pressure into the tank I.Likewise, passageway 1 of the top head 9 of tank 2 leads inwardly andjoins with an inlet hole ll opening downwardly through the center of thelower face of said head ii to form an inlet for air under pressure intotank 2.

Connected with one side of the casing of valve is an air inlet pipe l2leading to any suitable supply of compressed air. Connected with theopposite side of the casing of valve 5 is an exhaust pipe I3 leading tothe atmosphere, or any other point desired. Referring to Fig. 3, it willbe seen that the casing of valve 5 is formed with an opening M to whichsupply pipe [2 is connected, and an opening to which the exhaust pipe I3is connected. Said casing is also formed with an opening [6 to whichpipe 3 is connected, and. an opening I! to which pipe 4 is connected.The casing of valve 5 has rotatably mounted on its interior acylindrical valve member is having arcuate ports l9 and 20, sopositioned that when the valve member I8 is in the position shown inFig. 3 port 19 connects opening It and I5, and port 20 connects openingsI4 and I1. Rotation of valve member [8 through ninety degrees by anysuitable means, will bring one of said ports into communication withopenings [4 and i6, and the other into communication with ope ings l5and IT, as shown by dotted lines in Fig. 3. This construction, byselective operation of valve member i8, enables introduction of airunder pressure into either one of tanks 1 and 2 and exhaust of air fromthe other, as desired. It is thus seen that inlet holes [0 and Halternately function as exhaust or outlet holes.

Tanks I and 2 also have bottom heads 2| and 22 of construction similarto top heads 8 and 9,

bottom head 2! having an inlet (or outlet) hole 23 connected with apassageway leading to pipe 24, and bottom head 22 having an inlet (oroutlet) hole 25 connected with a passageway leading to pipe 26. Pipe 24at its opposite end is 0011- suitable liquid 32 therein and force it toone end of the work cylinder 28, to move its piston in a correspondingdirection, while the oil in the other end of the work cylinder isexhausted into the other tank and forces the air therein to exhaust.Upon completion of the above mentioned stroke of the piston, the valvemember it of the fourway valve 5 is rotated through ninety degrees,preferably automatically, and operation of the work cylinder and tanks 1and 2 takes place in the manner described above, but in the reversedirection.

In order to prevent churning and aeration of the oil, or other liquid,in tanks 5 and 2, there is provided in each of these tanks at each endof the interior thereof, a baffle, these four bafiles being indicated inl at 33-38. Each of these baffles is positioned away from the inner faceof the adjacent tank head a distance equal to onefcurth of the diameterof the hole of the inlet pipe in that head. The marginal edge of each ofthese bafiles is also spaced away from the side walls of the tank adistance equal to one-fourth of the diameter of the hoie of the inletpipe in the adjacent tank head. This provides an outwardly increasingarea for the oil or air passing through the inlet hole, and convertshigh velocity fiow in a small area passage into low velocity flow in alarge area passage. This so slows up the oil or air entering the tankthat it prevents churning and aeration of the oil in the tank, and

at the same time permits an easy flow into the tank of the oil or air,and an easy flow out of the tank when the operation of the work cylinderis reversed by the valve 5.

The same principle of bafile construction and operation is embodied inthe apparatus of Fig. 2, in which is shown a typical pump circuit havinga pump 31 connected in the supply pipe line 38, the pump drawing oil orother suitable liquid through pipe 39 which extends down into the bodyof oil 32' in tank 40. Pipe line 38 leads to a fourway valve 5, similarto valve 5 in Figs. 1 and 3. By manipulation of valve 5', oil underpressure from pump 31 may be selectively introduced through either pipe4| or pipe 42 to the desired end of work cylinder 43, to drive piston 44in the desired direction. When oil under pressure is passing throughpipe 4! to drive the piston, pipe 42 is functioning as the exhaust pipeto return the oil through valve 5, pipe 45 and into tank 30. When oilunder pressure is passing through pipe 42 to drive the piston in theopposite direction, the exhaust oil passes through pipe 4|, valve 5' andpipe 45 back to the tank 43. Pressure relief valve 46 is provided toreturn the oil back to the tank when a predetermined pressure in theline is exceeded.

Tank 40 is provided with a bafile 41 which is similar in construction,arrangement and operation to each of baflies 33-36, except for beingsomewhat larger in facial area and diameter. Regardless of the diameterof any of these'baflies, their perpendicular distance from the adjacentface of the tank head, and their marginal distance from the side wallsof the tank are onefourth of the diameter of the hole of the inlet pipein that head. Each of bafiies 33-36 and 41 are supported on the adjacenttank head by any suitable number of spaced lugs or spacing members 43,which firmly fix the bafiles in position but form practically noresistance to the flow of the fluid through the space between the baffleand he head.

The above described baffles are of especial value in fast cycling oilcircuits and make it possible to use much smaller oil tanks withoutchurning and aeration than was possible prior to the present invention.

The foregoing detailed description is given for clearness ofunderstanding only, and no unnecessary limitations should be understoodtherefrom, for some modifications will be obvious to those skilled inthe art.

Having described my invention, I claim:

In a fast cycling oil and air system for operating a work cylinder, apair of operatively connected tanks each having a heat at each end andadapted to receive a varying amount of oil, and air under pressurethereabove, each of said heads having an opening alternately serving asan inlet and an outlet, each of said heads having closely .cent theretoa net bafile fixed in the tank and extending parallel to its adjacenthead, the distance between the baiile and its respective head beingapproximately on -fourth of the diameter of said opening in that head,whereby to prevent c urning and aeration of the liquid in the tank.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 913,832 Lyon Mar. 2, 1909 2,969,714 Getchell Feb. 2, 19372,198,291 Poe M Apr. 23, 1940 2,207,057 Gulick July 9, 1940

